KR20070081782A - Composition of the sheath material for a power and/or telecommunication cable - Google Patents

Abstract

A composition for a sheath material of a power and/or telecommunication cable is provided to reduce manufacturing cost by using self-crosslinking instead of an expensive steam tube crosslinking process. A composition for a sheath material of a power and/or telecommunication cable includes synthetic compound, peroxides, and aminosilanes selected among a group consisting of ethylene/vinyl acetate copolymer, acrylonitrile, and polyurethane elastomer. The ethylene/vinyl acetate copolymer is included by 20-90 weight part, and contains vinyl acetate of 28-80%.

Description

Composition for exterior materials of power and / or communication cable {COMPOSITION OF THE SHEATH MATERIAL FOR A POWER AND / OR TELECOMMUNICATION CABLE}

The present invention relates to a crosslinkable composition for producing a cable sheathing material.

Particularly preferred but non-limiting uses of the invention exist in the field of power and / or communication cables.

The outermost sheath of the cable plays a very important role mechanically, thermally or chemically in terms of the protection of the cable.

When applied offshore, the outermost sheath of the cable should be particularly resistant to oil and oil sludge. For this purpose, the outermost sheath of the cable is usually made of hardened synthetic rubber.

Today, to prepare such materials, elastomeric composites which are generally crosslinked under high pressure and high temperature in a steam tube in the presence of sulfur or peroxide are commonly used.

However, this type of manufacturing process has the disadvantages of being complex and expensive to implement.

This is because steam tube crosslinking requires high pressure and high temperature, so it is necessary to use a relatively complex and energy consuming device. After all, the device is quite expensive to purchase, maintain, or use.

In addition, steam tube crosslinking reactions must meet particularly stringent safety standards.

Accordingly, a technical problem to be solved by the present invention is to provide a crosslinkable composition for exterior materials of power and / or communication cables, which has a relatively low manufacturing cost and still has excellent resistance to oil and petroleum sludge. Solving the problems of the prior art while ensuring the manufacture of the exterior material.

According to the present invention, a solution to the problems of the prior art is that the crosslinkable composition of the present invention is characterized in that the synthetic compounds, peroxides and also aminosilanes selected from the group consisting of ethylene / vinyl acetate copolymers, acetonitrile and polyurethane elastomers It is to include.

As described above, the present invention has the advantage of producing very special thermoplastic elastomers in that the thermoplastic elastomers can be crosslinked in ambient air for two weeks.

Thermoplastic elastomers, once crosslinked, make highly flexible materials with complete resistance to oil and petroleum sludge. Thus, the thermoplastic elastomers are very suitable for making cable sheaths for use offshore.

Self-crosslinking can avoid the use of costly steam tube crosslinking reaction processes, thus significantly saving manufacturing costs. The sheath according to the invention is preferably able to be produced simply by using a conventional thermoplastics manufacturing apparatus, which helps to lower the value of the thermoplastics. In addition, the ease of manufacture is a significant benefit in terms of industrial flexibility.

Although crosslinking of the composition according to the invention can take place in the atmosphere for a period of less than 3 weeks, it is possible to accelerate the crosslinking by increasing the temperature, ie by placing the thermoplastic elastomer in an oven at 85 ° C. for 12 hours. .

Particularly preferably, the role of the peroxide in chemical terms is to ensure good bonding of the ethylene / vinyl acetate copolymer on the one hand with the synthetic compound on the other hand for the purpose of producing a homogeneous mixture.

Thus, the ethylene / vinyl acetate copolymer is chemically bonded to the synthetic compound through a carbon-carbon bond.

Aminosilanes play a role in causing self-crosslinking.

Particularly preferably, the crosslinkable composition of the present invention comprises 20 to 90 parts by weight of ethylene / vinyl acetate copolymer with respect to 100 parts by weight of the resin. As used herein, the term "resin" generally means all polymers present in the crosslinkable composition.

Preferably, the ethylene / vinyl acetate copolymer comprises 28 to 80% of vinyl acetate.

According to another preferred feature of the invention, the crosslinkable composition of the invention comprises less than 40 parts by weight of the synthetic compound with respect to 100 parts by weight of the resin.

If the synthetic compound is a polyurethane elastomer, the polyurethane elastomer is preferably in the form of a polyester. Polyurethane elastomers in the form of polyethers can also be used sufficiently.

Especially preferably, the crosslinkable composition of the present invention contains a peroxide in an amount of 0.8 to 2.1 parts by weight based on 100 parts by weight of the resin.

Preferably, the peroxide has a decomposition temperature of 110 to 145 ° C, preferably 135 to 145 ° C.

The decomposition temperature is consistent with the temperature measured during the treatment process, or “mixing process” of the composition according to the invention, for example in an internal mixer.

According to another preferred feature of the present invention, the crosslinkable composition of the present invention comprises aminosilane in an amount of 1 to 4 parts by weight based on 100 parts by weight of the resin.

According to one feature of the invention, the crosslinkable compositions of the invention may also comprise at least one secondary polymer compatible with the ethylene / vinyl acetate copolymer.

This means that the base polymer of the facer can consist essentially of a mixture of polymers and the main resin of the facer is ethylene / vinyl acetate copolymer. This feature makes it possible to impart special mechanical properties to the enclosure and / or to control the extent thereof.

Preferably, the secondary polymer may be selected from the group consisting of high density polyethylene and maleic anhydride grafted polyethylene.

Especially preferably, the crosslinkable composition of the present invention contains the secondary polymer in a proportion of less than 40 parts by weight based on 100 parts by weight of the resin.

According to another feature of the invention, the crosslinkable composition of the invention further comprises at least one filler selected from the group consisting of flame-retardant fillers, extending fillers and reinforcing fillers. can do.

Where appropriate, the crosslinkable compositions of the invention will preferably comprise less than 190 parts by weight of filler relative to 100 parts by weight of resin.

According to another feature of the invention, the crosslinkable composition of the invention may also comprise at least one additive selected from the group consisting of stabilizers, antioxidants, colorants, processing aids and UV stabilizers.

Of course, the present invention relates to any power and / or communication cable comprising at least one sheath obtained with the above crosslinkable composition. In this form of appearance, the sheath may be an inner sheath or an outer sheath.

However, the present invention also relates to any power and / or communication cable comprising several insulated conductors extending along the interior of the same outer protective sheath as the outer protective sheath obtained with the crosslinkable composition described above.

Other features and advantages of the present invention will become more apparent from the following description of the comparative examples, which examples illustrate, but do not limit, the present invention.

compare Example

The purpose of the comparative example is to measure the resistance to oil and petroleum sludge of the two materials obtained with the composition according to the invention and compare it with the resistance to oil and petroleum sludge of similar thermoplastic elastomers which are not crosslinked. These three materials can be used for the manufacture of sheaths for power and / or communication cables.

Sample composition

The composition of Sample 1 corresponds to the composition of the prior art thermoplastic elastomers. The compositions of Samples 2 and 3 are consistent with the present invention in that they can produce crosslinked thermoplastic elastomers. Samples 2 and 3 are distinguished in that the synthetic compound is acrylonitrile for Sample 2, while the synthetic compound is polyurethane elastomer for Sample 3.

Table 1 details the composition of each of these three samples of materials 1, 2 and 3. The content mentioned in the above table is expressed in phr, ie parts by weight relative to 100 parts by weight of the resin.

Sample One 2 3 EVA 70 (phr) 75 60 50 EVA 28 (phr) 25 - - High Density Graft PE (phr) - 20 - Graft PE (phr) - - 20 Polyurethane (phr) - - 30 Nitrile (phr) - 20 - Peroxide (phr) 0.8 1.6 1.6 Aminosilane (phr) One 3.1 3.1 Flame Retardant Fillers (phr) 150 150 150 Antioxidant (phr) 0.5 0.5 0.5 Processing aid 2 2 2

"EVA 70" refers to an ethylene / vinyl acetate copolymer comprising 70% vinyl acetate. In this embodiment, the product is sold under the trade name LEVAPREN 700 by Bayer.

"EVA 28" also refers to an ethylene / vinyl acetate copolymer having a vinyl acetate content of only 28%. In this embodiment, the product is sold under the trade name ESCORENE 328 by Exxon.

"High Density Graft PE" consists essentially of high density maleic anhydride graft polyethylene and is sold under the name BYNEL 40E529 by DuPont.

"Graft PE" means maleic anhydride graft polyethylene, sold under the tradename OREVAC 18302 by Arkema.

"Polyurethane" means a polyurethane elastomer sold under the trade name UREPAN 641 G by Rhein Chemie.

"Nitrile" means acrylonitrile sold by Zeon.

The term "peroxide" actually means 2,5-dimethyl-2,5-di (tert-butylperoxy) -3-hexine (2,5-dimethyl-2,5-di (tert-butylperoxy) -3-hexyne ) Under the trade name TRIGONOX 145.45 by Akzo.

"Aminosilane" means γ-amino-propyltriethoxysilane supplied by Degussa.

A "flame retardant filler" consists of magnesium hydroxide (Mg (OH) ₂ ) and is a powder sold under the trade name MAGNIFIN H10 by Albermarle.

"Antioxidant" is a product sold under the trade name OA by Ciba.

The term "processing aid" relates to a product sold under the trade name STRUCKTOL WS180 by Strucktol.

Sample manufacturing

In fact, the preparation of each composition is carried out by injecting the various components into the internal mixer in a well defined order.

Thus, the manufacturing process started by injecting all the polymer compounds and peroxides simultaneously. In addition to peroxides, two ethylene / vinyl acetate copolymers, namely EVA 70 and EVA 28; Two synthetic compounds, namely acrylonitrile and polyurethane elastomers; And two secondary polymers formed of maleic anhydride graft polyethylene and high density maleic anhydride graft polyethylene.

Once the peroxides are completely decomposed, antioxidants can be added to the mixture. It is important to prevent antioxidants from consuming free radicals generated by peroxides so that the synthetic compound is bound to each ethylene / vinyl acetate copolymer.

The flame retardant filler and the remaining additives can be mixed at any time during this mixing step. Processing aids are preferably added before the end of the mixing step.

The material finally obtained was cooled and granulated in order to be able to extrude in the next step.

In the second step, the granules were injected into the extruder and aminosilane was added only at the actual extrusion time. Although the aminosilane can be injected in the liquid state by injection, it is preferred to mix in saturated form on the high density polyurethane porous support.

The extruded material in the defined shape was placed in an oven at 85 ° C. for 12 hours to accelerate crosslinking.

After cooling, the H2 test pieces were cut from several extruded shapes to obtain three types of samples, facers 1, 2 and 3.

Oil and petroleum Sludge  Resistance

In order to measure and compare the chemical resistance of the various samples, three types of standard tests were performed on the samples, each related to resistance to oil and petroleum sludge.

For each sample, the test procedure is roughly as follows:

First, the tensile strength and elongation at break of the sample were measured, and a conventional tensile test was conducted to establish a reference value. Such tensile tests are well known to those skilled in the art and are therefore not described further herein.

For each sample, three types of resistance tests were run individually, ie each time on a different piece of H2 test. These tests are described in standard NEK606.

The first resistance test consisted of immersing the test piece in an IRM902 oil bath at 100 ° C for 24 hours.

The second resistance test is very similar, but the only difference is that the test piece is immersed in an IRM902 oil bath at 100 ° C. for 70 hours.

The third resistance test consisted of immersing the test piece in a Carbosea bath at 70 ° C. for 56 days.

At the end of each resistance test, a tensile test was run again on the corresponding test piece to measure the increase or decrease in tensile strength and elongation at break.

Table 2 shows all the results for the three types of samples. "NM" means that the corresponding physical quantity cannot be measured substantially.

Sample One 2 3 Before test Tensile Strength (MPa) 8 8 9 Elongation at break (%) 188 160 150 Test 1 % Change in tensile strength -35 -4 -10 % Change in elongation at rupture 34 -12 8 Test 2 % Change in tensile strength -42 -11 -21 % Change in elongation at rupture -40 -26 -2 Test 3 % Change in tensile strength NM -25 3 % Change in elongation at rupture NM -20 -11

Looking at the "before test" result, it can be seen that the elongation value at the time of rupture of samples 2 and 3 is lower than the elongation value of sample 1. This confirms that the facing material obtained with the composition according to the invention has better mechanical properties than the materials of the prior art of essentially the same type but without crosslinking.

If one considers the results of several chemical resistance tests, a drop in mechanical properties is naturally observed in all three types of materials. However, this drop is much smaller for Sample 2 and Sample 3 compared to that measured for Sample 1. In fact, even less decreases and even sometimes increases in tensile strength and elongation at break are observed. It can also be seen that Sample 1 did not complete the third test successfully. This means that the facer obtained with the composition according to the invention provides excellent oil and petroleum sludge resistance.

Therefore, the crosslinkable composition according to the present invention has an advantage of providing a packaging material having excellent resistance to oil and petroleum sludge while having a considerably low manufacturing cost.

Claims (16)

In the crosslinkable composition for the exterior material of power and / or communication cable, A crosslinkable composition comprising an ethylene / vinyl acetate copolymer, a synthetic compound selected from the group consisting of acrylonitrile and polyurethane elastomers, peroxides, and aminosilanes. The method of claim 1, Crosslinkable composition, characterized in that it comprises 20 to 90 parts by weight of the ethylene / vinyl acetate copolymer with respect to 100 parts by weight of the resin. The method according to claim 1 or 2, The ethylene / vinyl acetate copolymer comprises 28 to 80% vinyl acetate. The method according to any one of claims 1 to 3, A crosslinkable composition comprising the synthetic compound in a proportion less than 40 parts by weight based on 100 parts by weight of the resin. The method according to any one of claims 1 to 4, The synthetic compound is a crosslinkable composition, characterized in that the polyurethane elastomer in the form of a polyester. The method according to any one of claims 1 to 5, A crosslinkable composition comprising the peroxide in an amount of 0.8 to 2.1 parts by weight with respect to 100 parts by weight of the resin. The method according to any one of claims 1 to 6, The peroxide has a decomposition temperature of 110 to 145 ° C, preferably 135 to 145 ° C. The method according to any one of claims 1 to 7, Crosslinkable composition comprising the aminosilane in a ratio of 1 to 4 parts by weight with respect to 100 parts by weight of the resin. The method according to any one of claims 1 to 8, And at least one secondary polymer compatible with the ethylene / vinyl acetate copolymer. The method of claim 9, The secondary polymer is selected from the group consisting of high density polyethylene and maleic anhydride grafted polyethylenes. The method of claim 9 or 10, A crosslinkable composition comprising the secondary polymer at a ratio of less than 40 parts by weight based on 100 parts by weight of the resin. The method according to any one of claims 1 to 11, And at least one filler selected from the group consisting of flame retardant fillers, extending fillers and reinforcing fillers. The method according to any one of claims 1 to 12, A crosslinkable composition comprising the filler in a proportion of less than 190 parts by weight with respect to 100 parts by weight of the resin. The method according to any one of claims 1 to 13, A crosslinkable composition further comprising at least one additive selected from the group consisting of stabilizers, antioxidants, colorants, processing aids and UV stabilizers. A power and / or communication cable comprising at least one sheath formed from the crosslinkable composition according to claim 1. In a power and / or communication cable in which several insulated conductors extend inside the same outer protective sheath, The power and / or communication cable, characterized in that the outer protective sheath is formed from the crosslinkable composition according to any one of claims 1-14.